When men grouped according to their aggressive/impulsive scores on standard psychological tests, are challenged with a serotonergic stimulator, such as fenfluramine, the neuroendocrine response is attenuated in the more aggressive, more impulsive men, suggestive of alterations in central serotonergic mechanisms. Further, results suggest that hostility ratings decrease with fenfluramine administration suggesting possible treatment rationales for the study. Aggression and impusivity may be important personality characteristics in initiating and perpetuating addictive behavior. In order to investigate mechanisms of this behavior, establish neuroendocrine markers, suggest treatment possibilities and assess the efficacy of treatment paradigms, we are extending these studies with the more specific serotonergic agonist, metachlorophenylpiperazine (mCPP). We are examining whether mCPP administration gives similar results to fenfluramine. Subsequent studies will examine serotonergic as well as dopaminergic secretion in greater detail. Using neurohormones as markers of these responses, secretion will be examined in the presence of either a serotonergic or dopaminergic agonist (mCPP or bromocryptine, respectively). Neuroendocrine provocation tests will be used to further define alterations of function in the aggressive men.